JPH01233786A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To facilitate independent detection of the respective light outputs of a plurality of light emitting points of a semiconductor laser with low crosstalk by a method wherein light beams emitted from the semiconductor laser propagate through respective different waveguides and are detected by respective different photodetectors provided in the waveguides. CONSTITUTION:A semiconductor laser 1 which has a plurality of light emitting points 1a, 1b and 1c is welded on a heatsink 3 and a substrate 2 which has a plurality of trenches immediately behind the end surface of the laser 1 is also provided on the heatsink 3. A waveguide 5 is composed of a tunnel formed with protrusions on both the sides of the trench of the substrate 2 and the heatsink 3. Photodetectors 4 are provided in the waveguides 5 by welding on the substrate 2 surface. If the end surface of the laser 1 and the incident surface of the substrate 2 are arranged close to each other, penetration of the light from the other light emitting point can be suppressed. With this constitution, the individual light outputs can be independently detected with low crosstalk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device capable of producing a plurality of stable light beams, which is used as a light source of an optical head of an optical disk device for high-speed data transfer.

[Conventional technology]

In order to improve the data transfer speed of optical disk devices, a method is known in which multiple tracks on an optical disk are simultaneously traced using multiple light beams, and information is recorded and reproduced in parallel on the multiple tracks.

At this time, it is advantageous to use a semiconductor laser having a plurality of light emitting points in the same package as the light source of the optical head in terms of reducing the number of parts, making the optical head smaller, and making it lighter. Furthermore, in order to stably and reliably perform information recording or reproducing operations, it is necessary to independently monitor and control the optical output of each light emitting point. In order to miniaturize the device, it is desirable to house the optical output monitor inside the laser package, as is done with ordinary one-beam semiconductor lasers.

Conventionally, a semiconductor laser device that emits a plurality of light beams is shown in FIGS. 3(a) and 3(b) ((a) is a plan view.

(b)' is a side view), the light emitting point 1a.

A wall or tunnel-shaped waveguide 5 is formed on the substrate 2 immediately after a light emitting point of an array type semiconductor laser in which a plurality of lbs and lcs are arranged to prevent the emitted light from other light emitting points from going around. The structure is such that the light emitted from the waveguide 5 is detected by a plurality of photodetectors 4 installed at the ends of the waveguide.

[Problem to be solved by the invention]

When a wall or tunnel-shaped waveguide is formed immediately after the light emitting point of the semiconductor laser and the light emitted from the waveguide is detected by multiple photodetectors, the light emitting point of the semiconductor laser and the waveguide It is necessary to make the distance between the input end of the waveguide and the distance between the light exit port of the waveguide and the photodetector close, and the position also needs to be accurate.

Since such a semiconductor laser device is small in size, it is difficult to accurately position it, and crosstalk is inevitable.As a result, accurate monitoring is not possible and the emitted light becomes unstable.

The object of the present invention is to solve the above-mentioned problems and provide a semiconductor laser device that can provide stable output light.

[Means to solve the problem]

The semiconductor laser of the present invention includes a semiconductor laser having a plurality of light emitting points that can be driven independently, a plurality of waveguides that propagate light emitted from the semiconductor laser independently for each light emitting point, and the waveguide. The semiconductor laser, the waveguide, and the photodetector are housed in the same package, and the waveguide is A surface of a substrate having a plurality of striped convex portions is bonded or fused onto a heat sink, and a region surrounded by the convex portions of the substrate and the heat sink is configured, and the photodetector is located inside the waveguide. It has a structure that is provided on the substrate surface.

[Effect]

In the present invention, light emitted from a plurality of light emitting points propagates inside different waveguides, and is detected by different photodetectors configured inside the waveguides. Independent detection of the individual light outputs is therefore possible with low strokes. Furthermore, since there is no need to attach an external photodetector, there is no need for positioning, which reduces the effort required for adjustment.

〔Example〕

FIG. 1 shows an embodiment of the present invention. FIG. 1(a) is a top view of the semiconductor laser device of the present invention, and FIG. 1(b) is a side view. A plurality of light emitting points 1a, 1b.

A semiconductor laser 1 having an IC is fused onto a heat sink 3, and a substrate 2 having a plurality of grooves is provided immediately after the end face of the semiconductor laser 1. The waveguide 5 consists of a tunnel-shaped portion formed by the convex portions on both sides of the groove of the substrate 2 and the heat sink 3.

The photodetector 4 was provided by being fused to the substrate surface inside the waveguide 5, as shown in FIG. 1(b). At this time, by placing the end face of the semiconductor laser 1 and the incident end face of the substrate 2 close to each other, it is possible to suppress light from going around from other light emitting points.

FIG. 2 is a perspective view of an example of a substrate having a waveguide in FIG. 1. As the material of the substrate, silicon, germanium, indium gallium arsenide, etc. are used, for example.

Figure 2(a) shows an example in which a photodetector is constructed by forming a groove on the substrate surface by etching or mechanical processing, and forming a pn junction on the inner surface of the groove by diffusion or ion implantation. . In Figure 2(b), photodetectors are arranged in an array on the substrate surface, and then a film is selectively applied on the dividing line of the arrayed photodetector using a method such as printing to form a step. This is an example. Note that the electrode of the photodetector can be provided by providing a through hole in the substrate 2 and taking it on the surface opposite to the surface with the step, or by drawing out the electrode above the step on the substrate 2.
The method used is to make contact with an electrode patterned on a heat sink.

In this embodiment, a semiconductor laser having three light emitting points has been described, but the same applies to a semiconductor laser having two or four or more light emitting points.

〔Effect of the invention〕

As explained above, in the semiconductor laser device of the present invention,
Since the photodetector is installed inside the waveguide, the light emitted from the semiconductor laser with multiple light emitting points propagates through different waveguides and is detected by different photodetectors inside the waveguide. Ru. Therefore, there is an effect that independent detection of each optical output is possible with low crosstalk.

[Brief explanation of the drawing]

FIG. 1 is a top view and side view showing one embodiment of the present invention, FIG.
The figures are a top view and a side view showing a conventional example. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Substrate, 3... Heat sink, 4... Photodetector, 5... Waveguide.

Claims (1)

[Claims] A semiconductor laser having a plurality of light emitting points that can be driven independently; a plurality of waveguides that propagate light emitted from the semiconductor laser independently for each light emitting point; The semiconductor laser, the waveguide, and the photodetector are housed in the same package, and the waveguide has a plurality of striped protrusions on its surface. The surface of the substrate having a convex portion is bonded or fused onto a heat sink, and the photodetector is provided on the surface of the substrate inside the waveguide. A semiconductor laser device characterized by: